This invention relates to a device for the rectilinear guiding of a body of a shed-forming device that can be driven in a go and fro movement.
In the Belgian patent publication no. 1 004 308 a drive system for the knife-supporting beams of a Jacquard machine is described whereby the knife-supporting beams perform a vertical up and down movement through driving of two follower levers located diametrically opposite each other via two complementary cam disks that are on both extremities of a central drive shaft. In order to prevent the knife-supporting beams from lateral oscillation during the up and down vertical movement, on both extremities of the knife-supporting beams a guide is provided that can be implemented as a roller set, sliding set or ball bushings on guide rods. The disadvantage of this type of guide is that this has to be abundantly lubricated and requires rather a lot of maintenance, which with textile machines is considered as a disadvantage. This guide is furthermore not very suitable for the operation of Jacquard machines with high speed.
In the European patent application no. 0 849 384 a drive system for the knife-supporting beams is described whereby the guiding in longitudinal direction of the knife-supporting beams is implemented by oscillating levers, which are secured to rods, which in their turn are connected via small connecting rods to a second series of levers. The aforesaid levers are on the extremity of a fixed tube in which there are two coaxially placed longitudinal shafts which perform an alternate rotary movement, whereby the aforesaid rotary movement is generated by transmission from the rotary movement of a drive shaft on the coaxially placed longitudinal shafts via a cam mechanism. The disadvantage of this device is that the pivoting point of the oscillating levers in the knife-supporting beam does not describe a straight line but an arc around a fixed pivot. Because of this during their up and down movement the knife-supporting beams undergo a small lateral movement perpendicular to the vertical movement. The lateral movement is then also transmitted to the knife supports through which the lifting knives experience more friction in the guide. The circular arc movement also gives rise to centrifugal forces through which the device is subjected to vibrations at high operating speed.
The purpose of the invention is to provide a device for the rectilinear guiding of a body of a shed-forming device that can be driven in a go and fro movement by which the above mentioned disadvantages are remedied.
This purpose is achieved by providing a device such as has been described in the first paragraph of this specification, but whereby the device comprises a rod mechanism of which a first and a second rod are rotatably connected to respectively the body and a fixed part, and whereby this rod mechanism is provided in order to exert a rectilinear movement on the joint between the body and the rod during the movement of the driven body. The advantage of this device is that the knife support beams will no longer perform any lateral movement and then also no centrifugal forces will occur. This device will cause less vibrations in the knife support beams and furthermore operate at higher operating speeds and will require no maintenance.
According to a particular embodiment of the device the joint between the first rod and the body can move in a straight line through the joint between the second rod and the fixed part.
In a preferred embodiment the first and the second rod are rotatably connected to each other, and the rod mechanism is so constructed that the joint between the second rod and the fixed part form the three angular points of an isosceles triangle and the first and the second rod always form a same angle in relation to the plane perpendicular to the direction of movement.
A significant characteristic of the invention is that the first rod is rotatably connected in a first joint on this first rod to the aforesaid body, the second rod is rotatably connected in a first joint on this second rod to the fixed part and the aforesaid first and second rod are rotatably connected to each other in a common second joint so that the distance between the first joints of the first and the second rod and the second joint for both rods is equal, and that means are provided to determine the positions of the rods in the course of the movement of the body so that the angle between the first rod and a plane perpendicular to the direction of movement is always equal to the angle between the second rod and a plane perpendicular to the direction of movement.
According to a preferred embodiment the first rod extends to past the common joint of the first and the second rod, and this is so guided that a point of the first rod located past the aforesaid common joint can move according to an almost horizontal movement path.
It is furthermore also preferred that the aforesaid point of the first rod and the aforesaid joint between the second rod and the fixed part lie in a same plane extending almost perpendicular to the direction of movement.
According to a preferred embodiment of the invention the first rod is rotatably connected past the joint to a third rod, which is rotatable in relation to a fixed point. The advantage of a hinge point as opposed to a point that has to perform a sliding movement, is that the aforesaid rotatable joint can be implemented with ball bearings that are sealed and are lubricated for life, so that these require no maintenance at all.
The rod mechanism preferably comprises only hinge points. This offers the same advantage as discussed in the preceding paragraph.
In a preferred embodiment of the invention the go and fro movement that is performed by the device is preferably an almost vertical movement.
In a preferred embodiment of the invention the aforesaid shed-forming device is a device of a machine of the Jacquard type.
In a preferred embodiment the aforesaid body is a knife-supporting beam.
This invention also relates to a drive system for knife-supporting beams (e.g. of a Jacquard machine) that is provided with a guiding device according to this invention.
This invention is preferably utilized by providing a Jacquard machine that is provided with at least one knife-supporting beam working together with a guiding device according to this invention.